Is Convert Sorted List to Binary Search Tree easy or hard?

Convert Sorted List to Binary Search Tree is rated Medium on LeetCode. The main challenge is recognizing that the middle element must become the root to maintain balance while handling linked list traversal efficiently.

How to solve Convert Sorted List to Binary Search Tree in O(n)?

Achieving O(n) time typically involves first copying the linked list values into an array. Once stored in an array, you can build a balanced BST by recursively choosing the middle element as the root. Each element is processed once, producing overall O(n) time.

Convert Sorted List to Binary Search Tree Python or Java solution?

Python and Java solutions usually follow two patterns: convert the linked list to an array and build the BST using the middle index, or use fast and slow pointers to find the middle node directly in the list. Both approaches recursively construct left and right subtrees.

What is the best approach for Convert Sorted List to Binary Search Tree?

The fast and slow pointer approach is usually considered the best interview solution. It finds the middle node of the linked list to use as the root and recursively builds left and right subtrees. This method avoids converting the list into another structure and uses only O(log n) recursion space.

What data structure is used in Convert Sorted List to Binary Search Tree?

The problem primarily uses a singly linked list as input and constructs a binary search tree as output. Solutions commonly rely on recursion, the fast–slow pointer technique, and divide-and-conquer to maintain BST ordering and balance.

What is the time complexity of Convert Sorted List to Binary Search Tree?

Time complexity depends on the approach. Converting the linked list to an array and then building a BST takes O(n) time. The fast–slow pointer approach repeatedly scans for the middle node, leading to O(n log n) time with O(log n) recursion stack space.

Is Convert Sorted List to Binary Search Tree asked at Google, Amazon, or Meta?

Convert Sorted List to Binary Search Tree appears in many technical interview prep lists and has been reported in interviews at companies like Amazon, Google, and Meta. The problem tests linked list traversal, recursion, and understanding of balanced binary search trees.

Description Solution Video 22:29

109. Convert Sorted List to Binary Search Tree

Medium67.4% acceptance9 companies

Given the head of a singly linked list where elements are sorted in ascending order, convert it to a height-balanced binary search tree.

Example 1:

Input: head = [-10,-3,0,5,9]
Output: [0,-3,9,-10,null,5]
Explanation: One possible answer is [0,-3,9,-10,null,5], which represents the shown height balanced BST.

Example 2: